Actin dynamics in the regulation of the function of hematopoietic stem cells

造血干细胞功能调节中的肌动蛋白动力学

• 批准号: 424702342
• 负责人: Professor Dr. Robert A.J. Oostendorp
• 金额: --
• 依托单位: Klinik und Poliklinik für Innere Medizin III: Hämatologie und Onkologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/424702342?language=en
• 关键词: Actin; dynamics; regulation; function; hematopoietic

In the previous funding period, we have found that in Wnt5a-haploinsufficient mice, HSCs are regenerated in normal numbers after transplantation. However, the regenerated HSCs (HSC-5a) are functionally defective and do not engraft secondary recipients. To understand this functional decline, we performed a transcriptome analysis. This analysis suggested that actin dynamics is deregulated in the HSC-5a, which was confirmed in experiments showing reduced adhesion, migration and homing. However, these diminished migratory properties do not explain the complete failure to engraft. Hence, in the current application, we propose to investigate how deregulation of actin dynamics drives the functional decline of HSCs. It is known that actin dynamics is not only required in migration, but also in endo- and exocytosis, as well as auto- and mitophagy. Indeed, our preliminary analyses showed an increased number of mitochondria in HSC-5a, suggestive of defective mitophagy. Here, we will test the hypothesis that HSC-5a suffer from a failure of an actin-dependent process to regulate the number of mitochondria. For this purpose, we will study mitochondrial mass and function in functionally deficient HSCs and their association with deregulated expression of the actin dynamics pathway. These HSCs will not only be generated in Wnt5a-haploinsuficient mice, but also isolated from Osx-Cre;Wnt5amice. Furthermore, we will modulate mitophagy, using small molecules inhibitors of actin dynamics or, alternatively, we will conditionally modulate the expression of actin dynamics genes which are upregulated in HSC-5a. Importantly, we will study whether these treatments or genetic manipulations will rescue in vitro behavior and repopulating HSC activity in vivo. These experiments will on the one hand increase our understanding of the coupling between actin dynamics, mitochondrial function, and HSC function, as well as identify additional actin dynamics pathway nodes which may facilitate normalization of mitochondria and rescue of HSC function. This knowledge may not only be of importance in understanding the functional decline of HSCs in normal regeneration and aging, but also in malignant disease associated with an aberrant niche such as aplastic anemia, chronic lymphocytic leukemia and myelodysplastic syndrome.

在之前的资助期间，我们发现在Wnt 5a-单倍不足的小鼠中，HSC在移植后以正常数量再生。然而，再生的HSC（HSC-5a）在功能上有缺陷，并且不能植入第二受体。为了了解这种功能下降，我们进行了转录组分析。该分析表明，HSC-5a中肌动蛋白动力学失调，这在显示粘附、迁移和归巢减少的实验中得到证实。然而，这些减少的迁移特性并不能解释移植的完全失败。因此，在本申请中，我们建议研究肌动蛋白动力学的失调如何驱动HSC的功能下降。已知肌动蛋白动力学不仅在迁移中需要，而且在胞内和胞吐以及自噬和线粒体自噬中也需要。事实上，我们的初步分析显示HSC-5a中线粒体数量增加，提示线粒体自噬缺陷。在这里，我们将测试的假设，HSC-5a遭受失败的肌动蛋白依赖的过程来调节线粒体的数量。为此，我们将研究功能缺陷的HSC中线粒体的质量和功能，以及它们与肌动蛋白动力学途径表达失调的关系。这些HSC不仅在Wnt 5a单倍缺陷小鼠中产生，而且还从Osx-Cre; Wnt 5a单倍缺陷小鼠中分离。此外，我们将使用肌动蛋白动力学的小分子抑制剂调节线粒体自噬，或者，我们将有条件地调节HSC-5a中上调的肌动蛋白动力学基因的表达。重要的是，我们将研究这些治疗或遗传操作是否会挽救体外行为并在体内重建HSC活性。这些实验一方面将增加我们对肌动蛋白动力学、线粒体功能和HSC功能之间的耦合的理解，以及鉴定可能促进线粒体正常化和HSC功能拯救的另外的肌动蛋白动力学途径节点。这些知识不仅对理解HSC在正常再生和衰老过程中的功能下降很重要，而且对与异常生态位相关的恶性疾病如再生障碍性贫血、慢性淋巴细胞白血病和骨髓增生异常综合征也很重要。